1. Field of the Invention
The present invention relates generally to resilient cement compositions comprising a hydraulic cement, an aqueous rubber latex and a rubber latex stabilizing surfactant and methods of cementing using the resilient cement composition.
2. Description of the Prior Art
Resilient hydraulic cement compositions are commonly utilized above ground level and below ground level. An example of below ground level cement operations involves cementing pipe strings such as casings and liners in well bores. In performing primary cementing, a resilient hydraulic cement composition is pumped into the annular space between the walls of the well bore and the exterior surfaces of the pipe string disposed therein. The resilient cement composition is permitted to set in the annular space thereby forming an annular sheath of hardened, resilient and substantially impermeable cement therein. The resilient cement sheath physically supports and positions the pipe string in the well bore and bonds the exterior surfaces of the pipe string to the walls of the well bore whereby the undesirable migration of fluids between zones or formations penetrated by the well bore is prevented.
The cement compositions utilized for cementing above or below ground often must develop high strength after setting and also have sufficient resiliency, i.e., elasticity and ductility, to resist the loss of bonds between the set cement composition and metal pipe or the like. Also, the cement composition must be able to resist cracking and/or shattering as a result of movements, impacts and shocks subsequently generated. The bond loss, cracking or shattering of the set cement allows leakage of fluids through the cement which can be highly detrimental.
The cement sheath in the annulus between a pipe string and the walls of a well bore often fail due to pipe movements which cause shear and compressional stresses to be exerted on the set cement. Such stress conditions are commonly the result of relatively high fluid pressure and/or temperatures inside the cemented pipe string during testing, perforating, fluid injection or fluid production. The high internal pipe pressure and/or temperature results in the expansion of the pipe string, both radially and longitudinally, which places stresses on the cement sheath causing it to crack or causing the cement bonds between the exterior surfaces of the pipe or the well bore walls or both to fail which allows leakage of formation fluids, etc.
Thus, there are needs for improved well cement compositions and methods whereby after setting, the cement compositions form highly resilient solid masses which have high compressive, tensile and bond strengths sufficient to withstand stresses without failure.